Buggy code:
public class MultiverseCore extends JavaPlugin implements Core , MVPlugin { private static final int Protocol = 6 ; public static boolean EnforceAccess ; public static boolean EnforceGameModes ; public static boolean PrefixChat ; public static boolean BedRespawn ; @ Override public String dumpVersionInfo ( String buffer ) { } @ Override public MultiverseCore getCore ( ) { } @ Override public void setCore ( MultiverseCore core ) { } @ Override public int getProtocolVersion ( ) { } private static final Logger log = Logger . getLogger ( "Minecraft" ) ; private static DebugLog debugLog ; public static boolean MobsDisabledInDefaultWorld = false ; private CommandHandler commandHandler ; private static final String tag = "[Multiverse-Core]" ; private MVPermissions ph ; private FileConfiguration multiverseConfig = null ; private WorldManager worldManager = new WorldManager ( this ) ; private MVPlayerListener playerListener = new MVPlayerListener ( this ) ; private MVEntityListener entityListener = new MVEntityListener ( this ) ; private MVPluginListener pluginListener = new MVPluginListener ( this ) ; private MVWeatherListener weatherListener = new MVWeatherListener ( this ) ; public UpdateChecker updateCheck ; public static int GlobalDebug = 0 ; private HashMap < String , MVPlayerSession > playerSessions ; private GenericBank bank = null ; private AllPay banker ; protected MVConfigMigrator migrator = new MVCoreConfigMigrator ( this ) ; protected int pluginCount ; private DestinationFactory destFactory ; private SpoutInterface spoutInterface = null ; private double allpayversion = 3 ; private double chversion = 1 ; private MVMessaging messaging ; @ Override public void onLoad ( ) { } public FileConfiguration getMVConfiguration ( ) { } public GenericBank getBank ( ) { } public void onEnable ( ) { } private boolean validateAllpay ( ) { } private boolean validateCH ( ) { } private void initializeDestinationFactory ( ) { } private void registerEvents ( ) { } public void loadConfigs ( ) { this . multiverseConfig = YamlConfiguration . loadConfiguration ( new File ( getDataFolder ( ) , "config.yml" ) ) ; <START_BUG> Configuration coreDefaults = YamlConfiguration . loadConfiguration ( this . getClass ( ) . getResourceAsStream ( ( ( ( ( File . separator ) + "defaults" ) + ( File . separator ) ) + "config.yml" ) ) ) ; <END_BUG> this . multiverseConfig . setDefaults ( coreDefaults ) ; this . multiverseConfig . options ( ) . copyDefaults ( true ) ; this . worldManager . loadWorldConfig ( new File ( getDataFolder ( ) , "worlds.yml" ) ) ; MultiverseCore . GlobalDebug = this . multiverseConfig . getInt ( "debug" , 0 ) ; MultiverseCore . EnforceAccess = this . multiverseConfig . getBoolean ( "enforceaccess" , false ) ; MultiverseCore . EnforceGameModes = this . multiverseConfig . getBoolean ( "enforcegamemodes" , true ) ; MultiverseCore . PrefixChat = this . multiverseConfig . getBoolean ( "worldnameprefix" , true ) ; MultiverseCore . BedRespawn = this . multiverseConfig . getBoolean ( "bedrespawn" , true ) ; this . messaging = new MVMessaging ( this ) ; this . messaging . setCooldown ( this . multiverseConfig . getInt ( "messagecooldown" , 5000 ) ) ; this . saveMVConfigs ( ) ; } public MVMessaging getMessaging ( ) { } private void registerCommands ( ) { } @ Deprecated public void loadWorlds ( boolean forceLoad ) { } @ Deprecated public boolean addWorld ( String name , Environment env , String seedString , String generator ) { } @ Deprecated public boolean removeWorldFromList ( String name ) { } @ Deprecated public boolean removeWorldFromConfig ( String name ) { } @ Deprecated public Boolean deleteWorld ( String name ) { } public void onDisable ( ) { } @ Override public MVPlayerSession getPlayerSession ( Player player ) { } public SafeTTeleporter getTeleporter ( ) { } public MVPermissions getMVPerms ( ) { } @ Deprecated public MVPermissions getPermissions ( ) { } @ Deprecated public PurgeWorlds getWorldPurger ( ) { } @ Override public boolean onCommand ( CommandSender sender , Command command , String commandLabel , String [ ] args ) { } public void log ( Level level , String msg ) { } public static void staticLog ( Level level , String msg ) { } public static void staticDebugLog ( Level level , String msg ) { } private String getAuthors ( ) { } public CommandHandler getCommandHandler ( ) { } public String getTag ( ) { } public Environment getEnvFromString ( String env ) { } public void showNotMVWorldMessage ( CommandSender sender , String worldName ) { } public void removePlayerSession ( Player player ) { } public int getPluginCount ( ) { } public void incrementPluginCount ( ) { } public void decrementPluginCount ( ) { } public AllPay getBanker ( ) { } public void setBank ( GenericBank bank ) { } public DestinationFactory getDestFactory ( ) { } @ Deprecated public com . onarandombox . utils . DestinationFactory getDestinationFactory ( ) { } public void teleportPlayer ( CommandSender teleporter , Player p , Location l ) { } private void checkServerProps ( ) { } public void setSpout ( ) { } public SpoutInterface getSpout ( ) { } public WorldManager getMVWorldManager ( ) { } @ Deprecated public com . onarandombox . utils . WorldManager getWorldManager ( ) { } public MVPlayerListener getPlayerListener ( ) { } public boolean loadMVConfigs ( ) { } public boolean saveMVConfigs ( ) { } }

Fix:
Configuration coreDefaults = YamlConfiguration . loadConfiguration ( this . getClass ( ) . getResourceAsStream ( "//defaults//config.yml" ) ) ;